Methods and system for managing uplink buffer at user equipment in tethered call mode

ABSTRACT

Wireless communications systems and methods related to uplink buffer management are provided. In some aspects, a user equipment receives a synchronization acknowledgment message destined for a device tethered to the user equipment and transmitted by an application server at a network to which the user equipment is connected. In some aspects, the synchronization acknowledgment message includes an application server receiver window size indicating available buffer space in a receive buffer of the application server. The user equipment can modify the application server receiver window size in the received synchronization acknowledgment message prior to transmitting the received synchronization acknowledgment to the tethered device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and the benefit of the U.S.Provisional Patent Application No. 63/198,914, filed Nov. 20, 2020,titled “Methods and System for Managing Uplink Buffer at User Equipmentin Tethered Call Mode,” which is hereby incorporated by reference in itsentirety as if fully set forth below and for all applicable purposes.

TECHNICAL FIELD

The present disclosure relates generally to communications systems, andmore particularly, to buffer management of at a user equipment tetheredto a personal device.

INTRODUCTION

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. These systems may be capable of supporting communicationwith multiple users by sharing the available system resources (e.g.,time, frequency, and power). A wireless multiple-access communicationssystem may include a number of base stations (BSs), each simultaneouslysupporting communications for multiple communication devices, which maybe otherwise known as user equipment (UE).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level, examples of such telecommunicationstandards including 5G New Radio (NR) standard and the 4G Long TermEvolution (LTE) standard.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Some aspects of the present disclosure disclose a method of wirelesscommunication performed by a user equipment (UE). In some aspects, themethod comprises receiving a synchronization acknowledgment (SYN-ACK)message destined for a device tethered to the UE and transmitted by anapplication server at a network to which the UE is connected. In someaspects, the SYN-ACK message includes an application server receiverwindow size indicating available buffer space in a receive buffer of theapplication server. Further, the method comprises modifying theapplication server receiver window size in the received SYN-ACK messageprior to transmitting the received SYN-ACK to the tethered device.

In some aspects, a user equipment (UE) comprises a memory; atransceiver; and at least one processor coupled to the memory and thetransceiver. In some aspects, the transceiver is configured to receive asynchronization acknowledgment (SYN-ACK) message destined for a devicetethered to the UE and transmitted by an application server at a networkto which the UE is connected. In some aspects, the SYN-ACK messageincludes an application server receiver window size indicating availablebuffer space in a receive buffer of the application server. Further, insome aspects, the at least one processor is configured to modify theapplication server receiver window size in the received SYN-ACK messageprior to transmitting the received SYN-ACK to the tethered device.

In some aspects, a non-transitory computer-readable medium (CRM) hasprogram code recorded thereon for wireless communication by a userequipment (UE). In some aspects, the program code comprises code forcausing the UE to receive a synchronization acknowledgment (SYN-ACK)message destined for a device tethered to the UE and transmitted by anapplication server at a network to which the UE is connected. In someaspects, the SYN-ACK message including an application server receiverwindow size indicating available buffer space in a receive buffer of theapplication server. Further, in some aspects, the program code comprisescode for causing the UE to modify the application server receiver windowsize in the received SYN-ACK message prior to transmitting the receivedSYN-ACK to the tethered device.

In some aspects, a user equipment (UE) comprises means for receiving asynchronization acknowledgment (SYN-ACK) message destined for a devicetethered to the UE and transmitted by an application server at a networkto which the UE is connected. In some aspects, the SYN-ACK messageincludes an application server receiver window size indicating availablebuffer space in a receive buffer of the application server. Further, insome aspects, the UE comprises means for modifying the applicationserver receiver window size in the received SYN-ACK message prior totransmitting the received SYN-ACK to the tethered device.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example wireless communicationssystem and an access network according to some aspects of the presentdisclosure.

FIG. 2 is a diagram illustrating tethering of a device to a UE accordingto some aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example of a base station (BS) anduser equipment (UE) in an access network according to some aspects ofthe present disclosure.

FIG. 4 is a block diagram illustrating an example architecture of a UEconnected to a tethered device according to some aspects of the presentdisclosure.

FIG. 5 is a signaling diagram illustrating uplink (UL) buffer managementby a UE connected to a tethered device according to some aspects of thepresent disclosure.

FIG. 6 is a flowchart of a method of wireless communication according tosome aspects of the present disclosure.

FIG. 7 is a diagram illustrating an example hardware implementation fora UE employing a processing system according to some aspects of thepresent disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunications systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example aspects, the functions described maybe implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100 according to some aspects of thepresent disclosure. The wireless communications system (also referred toas a wireless wide area network (WWAN)) includes base stations 102, UEs104, an Evolved Packet Core (EPC) 160, and another core network 190(e.g., a 5G Core (5GC)). The base stations 102 may include macrocells(high power cellular base station) and/or small cells (low powercellular base station). The macrocells include base stations. The smallcells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to asEvolved Universal Mobile Telecommunications System (UMTS) TerrestrialRadio Access Network (E-UTRAN)) may interface with the EPC 160 throughbackhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as Next Generation RAN(NG-RAN)) may interface with core network 190 through backhaul links184. In addition to other functions, the base stations 102 may performone or more of the following functions: transfer of user data, radiochannel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over backhaul links 134 (e.g., X2interface). The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 158. The D2D communication link 158 may use theDL/UL WWAN spectrum. The D2D communication link 158 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, FlashLinQ, WiMedia,Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

In some cases, some of the UEs may obtain or establish connection to theradio network via another UE, i.e., the devices may be tethered to theother device (e.g., the tethered UEs may lack their own directconnection to the radio network or a connection to the radio network viathe tethering UE may be preferred, for instance, because of a strongeror cheaper connection). For example, FIG. 2 shows an example diagramillustrating the tethering of a device 206 such as a personal computer(PC) to a UE 204, according to some aspects of the present disclosure.In some aspects, the UE 204 may be connected to the base station (BS)202 in tethered call mode, where data is exchanged between a client orapplication in the tethered device 206 and a client or application in anapplication server communicating with the tethered device 206 via the UE204 (and its connection 208 to the BS 202). In some aspects, thetethered device 210 may be connected to the UE 204 via a communicationlink such as but not limited to a universal serial bus (USB) cable, anethernet cable, a Bluetooth® connection or a Wi-Fi® connection. In somecases, the UE 204 effectively serves as a modem for the communicationbetween the tethered device 206 and the BS 202 (and the applicationserver on which is executing an application communicating with thetethered device 206 via the UE 204). In some aspects, the tethereddevice 206 can be a cellular phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal digital assistant (PDA), asatellite radio, a global positioning system, a multimedia device, avideo device, a digital audio player (e.g., MP3 player), a camera, agame console, a tablet, a smart device, a wearable device, a vehicle, anelectric meter, a gas pump, a large or small kitchen appliance, ahealthcare device, an implant, a sensor/actuator, a display, or anyother similar functioning device.

In some aspects, the UE 204 or modem may maintain buffers to regulatethe data that is being exchanged between the tethered device 206 and theBS 202. In some cases, the UE 204 or modem may maintain buffers to haveenough data to indicate a buffer status report (BSR) to the BS 202 to,for instance, receive grant from the BS 202 to communicate the data tothe BS 202. In some aspects, the UE 204 may also maintain a data flowcontrol (FC) mechanism to manage the flow of data between the UE 204 ormodem and the tethered device 206 (e.g., and client or applicationexecuting thereon and communicating with the BS 202). For instance, theUE 204 or modem may include a FC component (e.g., FC 414 in FIG. 4 )that manages the amount of data in a buffer in the UE 204 that is beingexchanged between the tethered device 206 and the BS 202.

Returning now to FIG. 1 , in some aspects, the wireless communicationssystem may further include a Wi-Fi access point (AP) 150 incommunication with Wi-Fi stations (STAs) 152 via communication links 154in a 5 GHz unlicensed frequency spectrum. When communicating in anunlicensed frequency spectrum, the STAs 152/AP 150 may perform a clearchannel assessment (CCA) prior to communicating in order to determinewhether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or another typeof base station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies,and/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz) hasextremely high path loss and a short range. The mmW base station 180 mayutilize beamforming 182 with the UE 104 to compensate for the extremelyhigh path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The core network 190 may include an Access and Mobility ManagementFunction (AMF) 192, other AMFs 193, a Session Management Function (SMF)194, and a User Plane Function (UPF) 195. The AMF 192 may be incommunication with a Unified Data Management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides QoS flow andsession management. All user Internet protocol (IP) packets aretransferred through the UPF 195. The UPF 195 provides UE IP addressallocation as well as other functions. The UPF 195 is connected to theIP Services 197. The IP Services 197 may include the Internet, anintranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service,and/or other IP services.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit reception point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or core network 190 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a large or small kitchenappliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., parking meter, gas pump,toaster, vehicles, heart monitor, etc.). The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Although the present disclosure and accompanying drawings may be focusedon 5G New Radio (NR), the concepts described herein may be applicable toother similar areas, such as LTE, LTE-Advanced (LTE-A), Code DivisionMultiple Access (CDMA), Global System for Mobile communications (GSM),and/or other wireless/radio access technologies.

FIG. 3 is a block diagram of a base station (BS) 310 in communicationwith a UE 350 in an access network according to some aspects of thepresent disclosure. In the DL, IP packets from the EPC 160 may beprovided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC servicedata units (SDUs), re-segmentation of RLC data PDUs, and reordering ofRLC data PDUs; and MAC layer functionality associated with mappingbetween logical channels and transport channels, multiplexing of MACSDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs,scheduling information reporting, error correction through HARQ,priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

According to various aspects of the present disclosure, at least one ofthe TX processor 368, the RX processor 356, and/or thecontroller/processor 359 may be configured to perform aspects inconnection with FIG. 1 . For example, the RX processor 356 may receive asynchronization acknowledgment (SYN-ACK) message destined for a devicetethered to the UE and transmitted by an application server at a networkto which the UE is connected. In some aspects, the SYN-ACK message mayinclude an application server receiver window size indicating availablebuffer space in a receive buffer of the application server. Further, insome aspects, the controller/processor 359 may modify the receiverwindow size in the received SYN-ACK message prior to re-transmitting(e.g., forwarding, transmitting, communicating, etc.) the receivedSYN-ACK to the tethered device.

FIG. 4 is a block diagram illustrating an example architecture of a UE400 connected to a tethered device 405 according to some aspects of thepresent disclosure. The architecture of the UE 400 may include multipleprotocol stack layers, including a first layer 402 and a second layer404. While the architecture of the UE 400 illustrates two layers,additional and/or different layers may be present in different aspectswithout departing from the scope of the present disclosure.

The first layer 402 may include L2 functionality, such as a PDCP layer,an RLC layer, and/or a MAC layer. For example, the first layer 402 mayinclude a MAC component 410, which may implement various functionalityof the MAC layer. In some aspects, the first layer 402 may include morethan one layer, including Layer 3 (L3), L2, and/or Layer 1 (L1) (e.g.,L1 may include a PHY layer). For example, the first layer 402 mayrepresent one or more layers that are procedurally below the secondlayer 404 in the protocol stack of the architecture of the UE 400.

Illustratively, the first layer 402 may include a flow control (FC)component 414. The FC component 414 may be implemented in hardware,software, firmware, or a combination thereof. The FC component 414 maymanage at least a portion of the data flow between the first layer 402and the second layer 404. For example, the FC component 414 may controlthe flow of packets from the second layer 404 to the first layer 402.

The first layer 402 may further include a MAC component 410. The MACcomponent 410 may be implemented in hardware, software, firmware, or acombination thereof. The MAC component 410 may encapsulate data (e.g.,packets) from an uplink buffer 412 in TBs sent during transmission timeintervals (TTIs) scheduled according to an uplink grant.

The second layer 404 may include at least one layer that is procedurallyimplemented above the first layer 402. For example, the second layer 404may include an application layer. Accordingly, the second layer 404 mayinclude an application 444, the instructions of which may be executed byan application processor (AP) 440.

Each of the first layer 402 and the second layer 404 may include memoryin which to queue data for transmission over a wireless network.According to various aspects, the first layer 402 may include an uplinkbuffer 412, a retransmission queue 462, and an L2 pipeline queue 464.The uplink buffer 412 may include an L2 buffer and/or modem buffer thatmay queue data for encapsulation in MAC TBs and, therefore, the uplinkbuffer 412 may be configured to queue data received from a higher layer(e.g., the second layer 404) to be transmitted over the wirelessnetwork. The retransmission queue 462 may be configured to queue datathat is to be retransmitted, such as packets that are dropped,corrupted, and/or negatively acknowledged (e.g., NACK'ed). The L2pipeline queue 464 may be configured to queue data of lower layer(s)(e.g., the first layer 402) that is to be transmitted over the wirelessnetwork, such as uplink control information, HARQ ACK/NACK data, etc.The aggregate data in the uplink buffer 412, the retransmission queue462, and the L2 pipeline queue 464 may be collectively referred to as L2data.

At the second layer 404, the AP 440 may be communicatively coupled withan AP-accessible memory 442. The AP-accessible memory 442 may queue data(e.g., packets) that is to be transmitted over the wireless network,e.g., for the application 444. Data queued in the AP-accessible memory442 may include application data 476 generated in association withexecution of the application 444 by the AP 440. In some cases, the dataqueued in the AP-accessible memory 442 may include the application data411 or other data associated with the tethered device 405 (e.g., whendata is communicated between the tethered device 405 and the applicationserver via the UE 400).

The AP-accessible memory 442 may have a capacity that is greater thanthe uplink buffer 412. For example, the AP-accessible memory 442 may beconfigured to queue approximately two or three megabytes (MB) of data,whereas the uplink buffer 412 may be configured to queue approximately512 kilobytes (kB) of data. However, other capacities are possible inother aspects.

In one aspect, the AP-accessible memory 442 may include double data rate(DDR) synchronous dynamic random-access memory (SDRAM) 446 a. The DDRSDRAM 446 a may be attached to a system cache 446 b. The AP 440 may beconfigured to queue application data 476 in the system cache 446 b, anddefer queuing application data 476 in the DDR SDRAM 446 a (e.g., untilthe system cache 446 b is flushed).

In one aspect, the AP-accessible memory 442 may additionally oralternatively include on-chip memory 446 c. The AP 440 may be configuredto queue application data 476 in the on-chip memory 446 c. If the systemcache 446 b is limited (e.g., due to current operations, such asvideo/graphics processing by the UE 400), then the on-chip memory 446 cmay be used as an addition and/or alternative to the system cache 446 b.For example, the on-chip memory 446 c may provide overflow support whenthe system cache 446 b is at or near capacity. That is, the AP 440 mayqueue application data 476 in the system cache 446 b until the systemcache 446 b is at or near capacity, and then the AP 440 may switch toqueuing application data 476 in the on-chip memory 446 c (e.g., untilthe system cache 446 b is flushed).

In some aspects, the tethered device 405 may be tethered to the UE 400so that the tethered device can use the UE 400 as a modem to connect tothe network or base station to which the UE 400 is connected andexchange data with an external or remote application server via the BS.In some aspects, the tethered device 405 may include an applicationlayer. For example, the tethered device 405 may include an application409, the instructions of which may be executed by an applicationprocessor (AP) 407. The AP 407 may also be communicatively coupled withan AP-accessible memory (not shown). The AP-accessible memory may queuedata (e.g., packets) that is to be transmitted over the communicationlink (e.g., linking or tethering the tethered device to the UE) totransfer the queued data to the external or remote application servervia the UE 400. Data queued in the AP-accessible memory may includeapplication data 411 generated in association with execution of theapplication 409 by the AP 407. For example, the data can be transmissioncontrol protocol (TCP) acknowledgment (ACK) messages generated inresponse to TCP data packets received at the tethered device 405 in adownlink transmission from the external or remote application server viathe BS and the UE 400.

A size of data or amount of data queued in memory may be referred to asa watermark (WM). Each WM may be expressed in a byte size (e.g., bytes,kB, and/or MB) and a respective WM may correspond to a data sizecurrently queued in one of the AP-accessible memory 442 or memory of thetethered device 405, the uplink buffer 412, the retransmission queue462, or the L2 pipeline queue 464. For example, the data size in theuplink buffer 412 may be referred to as an uplink WM 470, and the uplinkWM 470 may fluctuate as the uplink buffer 412 is drained and refilled.

In some aspects, multiple thresholds may be configured in associationwith the uplink buffer 412. For example, the uplink buffer 412 may beconfigured with a high threshold 420 a, a low threshold 420 b, and/or ado not exceed (DNE) threshold 420 c. One or more of these thresholds 420a-c may be configured by a 3GPP mode handler based on an RRCconfiguration that is indicated to the UE 400 (e.g., via RRC signaling)and/or may be dynamically configured (e.g., based on observinghistorical trends associated with draining and refilling the uplinkbuffer 412). The thresholds 420 a-c may be compared with the uplink WM470.

According to an aspect, the FC component 414 may monitor and manage oneor more of the thresholds 420 a-c. The FC component 414 may send one ormore messages 472 to the AP 440. The AP 440 may send one or moremessages 474 to the FC component 414. For example, when the DNEthreshold 420 c is reached (e.g., the uplink WM 470 is equal to orexceeds the DNE threshold 420 c), the FC component 414 may signal the AP440 to cease sending data to the uplink buffer 412. Therefore, the AP440 may continue to queue data that is to be sent over the wirelessnetwork (e.g., data from the application 444) at AP-accessible memory442 and/or the AP 440 may allocate other memory in which to queue thedata while the uplink buffer 412 is emptied (e.g., by transmitting orotherwise removing the data in the uplink buffer 412). When the DNEthreshold 420 c is reached, data sent from the AP 440 may be droppedbecause the uplink buffer 412 is at or near capacity.

As another example, when the DNE threshold 420 c is reached, the FCcomponent 414 may prevent or pause the data exchange, via the UE 400,between the tethered device 405 and the external or remote applicationserver. For instance, the FC component 414 may close the communicationlink between the tethered device 405 and the UE 400 to prevent data fromthe tethered device 405 from arriving at the UE 400. When the DNEthreshold 420 c is reached, data sent from the AP 407 may be droppedbecause the uplink buffer 412 is at or near capacity. In some cases, theFC component 414 may also signal the tethered device 405 (e.g., the AP407) to cease sending data to the uplink buffer 412.

In another example, when the low threshold 420 b is reached (e.g., theuplink WM 470 is equal to or below the low threshold 420 b), the FCcomponent 414 may signal the AP 440 to resume sending data to the uplinkbuffer 412, e.g., from the AP-accessible memory 442.

In yet another example, when the high threshold 420 a is reached (e.g.,the uplink WM 470 is equal to or above the high threshold 420 a), the FCcomponent 414 may determine that no additional data should be queued inthe uplink buffer 412. The FC component 414 may generate an FC messageindicating that no more data should be sent to the first layer 402 to bequeued in the uplink buffer 412. The FC component 414 may send such anFC message to the second layer 404 in order to instruct the AP 440 torefrain some sending additional data to the first layer 402.

In some aspects, when the uplink WM 470 is less than the high threshold420 a or the low threshold 420 b, the FC component 414 may maintain thecommunication link between the tethered device 405 and the UE 400 openso that data may be transmitted from the tethered device to the remoteor external application server via the UE 400. For instance, if the WM470 falls below the high threshold 420 a after reaching the highthreshold 420 a or the DNE threshold 420 c, the FC component 414 mayopen the closed communication link so that data queued at the tethereddevice 405 may start flowing to the UE via the communication link (e.g.,to be transferred via the UE and the BS the UE is connected to arrive atthe remote or external application server). As noted above, an exampleof such data can be TCP ACK messages acknowledging downlinktransmissions transmitted to the tethered device 405 by the applicationserver. In some cases, when the low threshold 420 b is reached (e.g.,the uplink WM 470 is equal to or below the low threshold 420 b), the FCcomponent 414 may signal the AP 407 of the tethered device 405 to resumesending data to the uplink buffer 412.

In various aspects, the low threshold 420 b may be configured to beapproximately equal to a data size needed to serve T milliseconds (ms)worth of uplink peak rate transmission. By way of illustration, T may beequal to four ms, each TTI may be equal to 200 microseconds (μs), andthe peak MAC TB size per TTI may be equal to eight kB. Therefore, thelow threshold 420 b may be configured as 160 kB, which is equal to T msdivided by the TTI duration multiplied by the peak TB size or,equivalently in this example, (4 ms/200 μs)*8 kB. In some aspects, thelow threshold 420 b may be configured to be greater than the data sizeneeded to serve T ms worth of uplink peak rate transmission—e.g., thelow threshold 420 b may be configured as 200 kB.

The high threshold 420 a may be configured to be greater than the lowthreshold 420 b. For example, the high threshold 420 a may be configuredto be twice the low threshold, such as 400 kB. The DNE threshold 420 cmay be configured to be greater than the high threshold 420 a. Forexample, the DNE threshold 420 c may be configured to be 100 kB or 200kB greater than the high threshold 420 a. The thresholds 420 a-c may beconfigured to have different values in other aspects.

When the uplink buffer 412 includes data, the uplink buffer 412 may beemptied. The MAC component 410 may determine the uplink WM 470 thatindicates the data size currently queued in the uplink buffer 412. Forexample, the MAC component 410 may periodically poll the uplink buffer412 to receive the uplink WM 470. In another example, the FC component414 may indicate to the MAC component 410 that the uplink WM 470 hasreached at least one of the high threshold 420 a or the DNE threshold420 c, and the MAC component 410 may determine the uplink WM 470 basedon the indication from the FC component 414.

Based on the uplink WM 470, the MAC component 410 may send, to a basestation, an uplink grant request 422 in order to obtain an uplink grantfor sending the data queued in the uplink buffer 412. The uplink grantrequest 422 may include a BSR or buffer occupancy report. For example,the uplink grant request 422 may be based on the uplink WM 470.

In addition to the uplink WM 470, the MAC component 410 may generate anuplink grant request 422 based on an amount of data (e.g., packets) inthe retransmission queue 462 and/or the L2 pipeline queue 464. Thus, theMAC component 410 may generate the uplink grant request 422 based on thesum of the uplink WM 470, a WM of the AP-accessible memory 442, a WM ofthe memory of the tethered device 405, a WM of the retransmission queue462, and a WM of the L2 pipeline queue 464.

FIG. 5 is a signaling diagram illustrating uplink (UL) buffer managementby a UE connected to a tethered device according to some aspects of thepresent disclosure. The UE 502 can be the UE 104, UE 204, UE 350, or UE400, the tethered device 504 can be tethered device 206, or tethereddevice 405 and the base station (BS) 506 can be the BS 102, BS 202, orBS 310. In some aspects, the tethered device 504 may be communicating orexchanging data with an application server 508 via the UE 502 and the BS506 to which the application server 508 is connected. In some aspects,discussions herein related to the tethered device 504 establishing aconnection to and communicating or exchanging data with the BS 506 viathe UE 502 may also apply to, and is to be understood to include, theprocess of the tethered device 504 establishing the connection to andcommunicating or exchanging data with the application server 508 via theUE 502 and the BS 506 (e.g., as the application server may be part of orconnected to the network of which the BS 5606 is a part).

In some aspects, the communication link linking the tethered device 504to the UE 502 can be a universal serial bus (USB) cable, an ethernetcable, a Bluetooth® connection or a Wi-Fi® connection. In some aspects,the tethered device 206 can be a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a smart device, a wearabledevice, a vehicle, an electric meter, a gas pump, a large or smallkitchen appliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device.

In some aspects, the tethered device 504 may use the UE 502 as a modemfor connecting to the BS 506 to which the UE 502 is connected. In someaspects, the term “tethering” may refer to a device (e.g., such as thetethered device 504) using another device (e.g., such as the UE 502) asa modem to connect to a network to which the other device (i.e., the UE502) is connected (e.g., and use the connection for data exchange). Insome cases, the tethered device 504 may not have a connection to anapplication server coupled to a network (e.g., 5G NR, LTE, etc.,network) of which the BS 506 is apart, and may use the UE 502 to connectto the application server. For instance, the application server may be aserver hosting an application and the tethered device 504 may use the UE502 to receive data generated by the application (e.g., videos, audio,etc.).

In some aspects, the transmission control protocol (TCP) establishingconnection between the tethered device 504 and the BS 506 (e.g., and theapplication server 508 in connection with the BS 506) may be a three-wayhandshake where the tethered device 504 initiating the connection maytransmit to the application server 508 a synchronization (SYN) messageand the application server 508 may acknowledge the arrival of the SYNmessage to the tethered device 504 by transmitting to the tethereddevice 504 a synchronization acknowledgement (SYN-ACK) message inreturn. In some cases, after the connection is established between thetethered device 504 and the BS 506/application server 508,acknowledgments (ACKs) may be exchanged in response to received datatransmissions. For example, TCP downlink transmissions including datapackets may be transmitted from the application server 508 to thetethered device 504 via the UE 502 and the tethered device 504 maytransmit back to the application server 508 via the UE 502 an ACK toacknowledge the arrival of the data packets.

In some aspects, the SYN message and the SYN-ACK messages exchangedbetween the tethered device 504 and the application server 508 as partof the establishment of a TCP connection therebetween may includeparameters controlling data exchange between the tethered device 504 andthe application server 508. For instance, the SYN message from thetethered device 504 to the application server 508 may include a receiverwindow size of the tethered device that indicates to the applicationserver 508 the maximum amount of data that the tethered device 504 isconfigured to receive and buffer from the application server 508 (e.g.,before having to send an ACK to the application server 508 as anacknowledgement of the received data). In some aspects, the SYN-ACKmessage from the application server 508 to the tethered device 504 mayinclude a receiver window size of the application server 508 thatindicates to the tethered device 504 the maximum amount of data that theapplication server 508 is configured to receive and buffer from thetethered device 504 (e.g., before having to send an ACK to the tethereddevice 504 as an acknowledgement of the received data), i.e., theavailable buffer space in the receive buffer of the application server508.

In some aspects, as discussed above with reference to FIG. 4 , the UE502 may have associated therewith a buffer (e.g., an uplink (UL) buffer412). For example, the UE 502 which serves as a modem for the tethereddevice 504 and facilitates the exchange of data between the tethereddevice 504 and the application server 508 may have an uplink buffer forUL data being transmitted from the tethered device 504 to theapplication server 508. In some aspects, the UE 502 may close thecommunication link between the tethered device 504 and the UE 502, orotherwise prevent the transmission of UL data from the tethered device504, when the UL buffer of the UE 502 is full.

For example, the UL buffer of the UE 502 may have an UL buffer thresholdassociated therewith where when the uplink watermark of the UE 502,i.e., the amount of data in the buffer of the UE 502, exceeds the ULbuffer threshold, the UE 502 closes the communication link between theUE 502 and the tethered device 504 so that data may not flow from thelatter to the former until the communication link is opened back upagain. In some cases, instead of or in addition to closing thecommunication link, the UE 502 may signal to the tethered device 504 tocease sending data to the UE 502 (e.g., data destined for theapplication server 508) until the UE 502 signals to the tethered device504 otherwise. In some instances, the UL buffer threshold may includemultiple thresholds (e.g., the low, high and DNE thresholds discussedwith reference to FIG. 4 ) and the UE 502 may close the communicationlink and/or signal the tethered device 504 to cease sending additionaldata to the UE 502 when the WM of the buffer exceeds the high thresholdor the DNE threshold.

In some aspects, when the WM of the UL buffer of UE 502 exceeds the ULbuffer threshold, the communication link between the UE 502 and thetethered device 504 may repeatedly close and open dynamically and causedelay in the UL transmission of ACKs from the tethered device 504 to theapplication server 508. For example, the application server 508 and thetethered device may be communicating and an application executing on theapplication server 508 may transmit data packets as TCP DL transmissionto the tethered device 504 via the BS 506 and the UE 502. For instance,the application server 508 may be transmitting the TCP DL data packetsaccording to a schedule of downlink (DL) transmission per a prior DLgrant.

Upon receiving the TCP DL data packets, in some cases, the tethereddevice 504 may generate a TCP ACK message to acknowledge the arrival ofthe TCP DL data packets and send the ACK to the UE 502 for furthertransmission to the application server 508. In such cases, if thebuffering of the TCP ACK message (e.g., along with any other UL datatransmitted by the tethered device 504) at the UL buffer of the UE 502results in the WM of the UL buffer of UE 502 exceeding the UL bufferthreshold, the UE 502 may receive at most a portion of the datatransmitted by the tethered device 504 (e.g., the received at mostportion being such that the WM does not exceed the UL buffer threshold)and close the communication link between the UE 502 and the tethereddevice 504 until the WM falls below the UL buffer threshold (e.g., inwhich case the UE 502 may reopen the communication link to allow atleast some of the rest of the transmitted data arrive at the UL bufferof the UE 502). In some cases, this process may occur repeatedly,causing TCP ACKs transmitted by the tethered device 504 and destined forthe application server 508 to be stalled at the UE 502, resulting inincreased round trip time (RTT) between the tethered device 504 and theapplication server 508, which in turn may affect (e.g., delay or reduce)the scheduling of DL transmissions from the application server 508 tothe tethered device 504. In some cases, RTT refers to the round triptime between a sender sending a data packet or signal to a receiver andreceiving in return, from the receiver, an ACK acknowledging the arrivalof the data packet or signal at the receiver. In some aspects, the UEmay monitor the RTT of a communication cycle between the applicationserver and the tethered device. In some aspects, the communication cyclemay include data being transmitted by the application server via the UEto the tethered device and an acknowledgement being received at theapplication server after transmission via the UE by the tethered devicein response to the data being received at the tethered device. In someaspects, the UE may determine, based on monitoring the RTT, that the RTTis increasing over time. In some cases, the UE may modify theapplication server receiver window size based on determining the RTT isincreasing over time.

Some aspects of the present disclosure disclose a mechanism for ULbuffer management of a UE such that UL transmissions from a devicetethered to the UE destined for an external or remote application serverare not stalled at the UE due to overflowing or full UL buffer at theUE. In some aspects, with reference to FIG. 5 , a device 504 may betethered to a UE 502 via a communication link such as but not limited toa USB cable, an ethernet cable, a Bluetooth® connection, a Wi-Fi®connection, etc., to use the UE 502 as a modem to establish a TCPconnection to an application server 508 via the BS 506 to which the UE502 is connected. In some aspects, to establish the TCP connection withthe application server 508, the tethered device 504 may initiate athree-way handshake by transmitting to the application server 508 a SYNmessage 510 (e.g., via the UE 502 and the BS 506). In some instances,the SYN message 510 may include parameters of the tethered device 504related to the transmission and reception of data at the tethered device504, such as but not limited to tethered device send window sizeindicating available buffer space in a send buffer of the tethereddevice 504, tethered device receiver window size indicating availablebuffer space in a receive buffer of the tethered device 504 (e.g., themaximum amount of data that the tethered device 504 is configured toreceive and buffer from the application server 508, for instance, beforehaving to send an ACK to the application server 508 as anacknowledgement of the received data), etc. In some cases, the tethereddevice send window size may also be bounded by the receiver window sizeof the application server 508, i.e., the tethered device send windowsize may be no greater than the receiver window size of the applicationserver 508 (e.g., besides being bounded by, i.e., being no greater than,the send buffer of the tethered device 504).

In some aspects, upon receiving the SYN message 510 from the tethereddevice 504, the application server 508 may generate a SYN-ACK message512 that acknowledges the arrival of the SYN message 510 at theapplication server 508 and send the SYN-ACK 512 to the UE 502 forfurther transmission to the tethered device 504. In some aspects, theSYN-ACK message 512 may include parameters of the application server 508related to the transmission and reception of data at the applicationserver 508, such as but not limited to application server send windowsize indicating available buffer space in a send buffer of theapplication server 508, application server receiver window sizeindicating available buffer space in a receive buffer of the applicationserver 508 (e.g., the maximum amount of data that the application server504 is configured to receive and buffer from the tethered device 508,for instance, before having to send an ACK to the tethered device 504 asan acknowledgement of the received data), etc. In some cases, theapplication server send window size may also be bounded by the receiverwindow size of the tethered device 504, i.e., the application serversend window size may be no greater than the receiver window size of thetethered device 504 (e.g., besides being bounded by, i.e., being nogreater than, the send buffer of the application server 508).

In some aspects, upon receiving the SYN-ACK message 512 from theapplication server 508, the UE 502 may modify 514 the received SYN-ACKmessage 512 to alter at least some of the parameters of the applicationserver 508 related to the transmission and reception of data at theapplication server 508. That is, in some aspects, the UE 502 mayintercept at the UE 502 the SYN-ACK message 512 destined for thetethered device 504 and modify at least some of the parameters of theapplication server 508 related to the transmission and reception of dataat the application server 508. In some cases, the modification to theparameters may comprise modifying the receiver window size of theapplication server 508 that is included in the SYN-ACK message 512. Forexample, the UE 502 may modify the received or intercepted SYN-ACKmessage 512 to change (e.g., reduce) the receiver window size of theapplication server 508 in the SYN-ACK message 512 so that the receiverwindow size may not exceed the UL buffer threshold of the UE 502.Further, because the tethered device send window size can be bounded by,i.e., can be no greater than, the receiver window size of theapplication server 508, modifying the receiver window size of theapplication server 508 in the SYN-ACK message 512 to be no greater thanthe UL buffer threshold of the UE 502 may result in the tethered devicesend window size also being no greater than the UL buffer threshold ofthe UE 502. That is, the UE 502 may modify the SYN-ACK message 512 byreducing the receiver window size of the application server 508 in theSYN-ACK message 512 to be no greater than the UL buffer threshold of theUE 502, which may result in tethered device send window size also beingno greater than the UL buffer threshold of the UE 502.

In some aspects, after modifying 514 the SYN-ACK message 512 interceptedor received from the application server 508, the UE 502 may then sendthe modified SYN-ACK message 516 to the tethered device 504. In someaspects, after receiving the modified SYN-ACK message 516 from the UE502, the tethered device 504 may limit the size of UL transmissions fromthe tethered device 504 to the application server 508 to be no greaterthan the UL buffer threshold of the UE 502 (e.g., because the tethereddevice send window size is bounded or limited by the reduced receiverwindow size of the application server 508 in the SYN-ACK message 512that is modified by the UE 502, where the reduced receiver window sizeis reduced by the UE 502 to be no greater than the UL buffer thresholdof the UE 502). As such, the WM of the UL buffer of UE 502 may notexceed the UL buffer threshold because of an UL communication from thetethered device to the application server 508, and the UE 502 may keepthe communication link 518 between the tethered device 504 and the UE502 open, which allows UL transmissions such as TCP ACK messages fromthe tethered device 504 acknowledging arrival at the tethered device 504of TCP DL data packets transmitted by the application server 508 may betransmitted to the application server 508 without being stalled ordelayed at the UE 502 because of a closed communication link (e.g., or asignal from the UE 502 to the tethered device 504 instructing thetethered device to cease transmissions of the TCP ACK messages).

In some aspects, the tethered device 504 may comprise multiple devicestethered to the UE 502. In such cases, the sum of the tethered devicesend window sizes of the multiple devices may be bounded or limited bythe reduced receiver window size of the application server 508, which isreduced by the UE 502 to be no greater than the UL buffer threshold ofthe UE 502. As such, the WM of the UL buffer of UE 502 may not exceedthe UL buffer threshold due to UL communications from the multipletethered devices to the application server 508, and the UE 502 may keepthe communication link 518 between the multiple tethered devices and theUE 502 open.

Although FIG. 5 shows modification to SYN-ACK from the applicationserver 508 to the tethered device 504, same or similar modification mayalso occur to the traffic in the opposite direction. That is, a SYN-ACKfrom the tethered device 504 to the application server 508 may bemodified in at least substantially similar manner as discussed herein tocontrol the data traffic from the application server 508 to the tethereddevice 504.

FIG. 6 is a flow chart illustrating a method 600 of wirelesscommunication. The method 600 may be performed by a UE and/or apparatus,such as the UE 104, the UE 204, the UE 350, the UE 400, the UE 502, theapparatus 702/702′, which may include the memory 360 and which may bethe entire UE 350 or a component of the UE 350 (e.g., the TX processor368, the RX processor 356, and/or the controller/processor 359). The UEand/or apparatus may include at least a first layer, such as a PHYand/or MAC layer, and a second layer, such as an application layer.According to various aspects, one or more of the illustrated operationsof the method 600 may be omitted, transposed, and/or contemporaneouslyperformed. As illustrated, the method 600 includes a number ofenumerated steps, but aspects of the method 600 may include additionalsteps before, after, and in between the enumerated steps. In someaspects, one or more of the enumerated steps may be omitted or performedin a different order.

In some aspects, at operation 602, a UE may receive a synchronizationacknowledgment (SYN-ACK) message destined for a device tethered to theUE and transmitted by an application server at a network to which the UEis connected. In some aspects, the SYN-ACK message may include anapplication server receiver window size indicating available bufferspace in a receive buffer of the application server.

In some aspects, at operation 604, the UE may modify the receiver windowsize in the received SYN-ACK message prior to re-transmitting (e.g.,forwarding, transmitting, communicating, etc.) the received SYN-ACK tothe tethered device.

In some aspects, the UE may further determine that an amount of datatransmitted by the tethered device to the application server via the UEexceeds an uplink (UL) buffer threshold of the UE, for instance, priorto the modifying the receiver window size. In some aspects, modifyingthe application receiver window size includes reducing the applicationreceiver window size to less than or equal to the UL buffer threshold ofthe UE.

In some aspects, the UE may further monitor, prior to the modifying thereceiver window size, a round trip time (RTT) of a communication cyclebetween the application server and the tethered device. In some aspects,the communication cycle may include data being transmitted by theapplication server via the UE to the tethered device and anacknowledgement being received at the application server aftertransmission via the UE by the tethered device in response to the databeing received at the tethered device. In some aspects, the UE maydetermine that the RTT is increasing over time.

In some aspects, the UE may receive a synchronization (SYN) messagedestined for the application server via the UE and transmitted by thetethered device to establish a transmission control protocol (TCP)connection with the network. In some aspects, the SYN may include adevice receiver window size indicating a maximum amount of data thetethered device is configured to receive and buffer.

In some aspects, the device tethered to the UE can be a personalcomputer tethered to the UE via a communication link including auniversal serial bus (USB) cable, an ethernet cable, a Bluetooth®connection or a Wi-Fi® connection.

FIG. 7 is a diagram 700 illustrating an example of a hardwareimplementation for an apparatus 702. The apparatus 702 is a UE andincludes a cellular baseband processor 704 (also referred to as a modem)coupled to a cellular RF transceiver 722 and one or more subscriberidentity modules (SIM) cards 720, an application processor 706 coupledto a secure digital (SD) card 708 and a screen 710, a Bluetooth module712, a wireless local area network (WLAN) module 714, a GlobalPositioning System (GPS) module 716, and a power supply 718. Thecellular baseband processor 704 communicates through the cellular RFtransceiver 722 with the UE 104 and/or BS 102/180. The cellular basebandprocessor 704 may include a computer-readable medium/memory. Thecellular baseband processor 704 is responsible for general processing,including the execution of software stored on the computer-readablemedium/memory. The software, when executed by the cellular basebandprocessor 704, causes the cellular baseband processor 704 to perform thevarious functions described supra. The computer-readable medium/memorymay also be used for storing data that is manipulated by the cellularbaseband processor 704 when executing software. The cellular basebandprocessor 704 further includes a reception component 730, acommunication manager 732, and a transmission component 734. Thecommunication manager 732 includes the one or more illustratedcomponents. The components within the communication manager 732 may bestored in the computer-readable medium/memory and/or configured ashardware within the cellular baseband processor 704. The cellularbaseband processor 704 may be a component of the UE 350 and may includethe memory 360 and/or at least one of the TX processor 368, the RXprocessor 356, and the controller/processor 359. In one configuration,the apparatus 702 may be a modem chip and include just the basebandprocessor 704, and in another configuration, the apparatus 702 may bethe entire UE (e.g., see 350 of FIG. 3 ) and include the aforementionedadditional modules of the apparatus 702.

The communication manager 732 includes a SYN-ACK modifier component 740that is configured to receive a synchronization acknowledgment (SYN-ACK)message destined for a device tethered to the UE and transmitted by anapplication server at a network to which the UE is connected, e.g., asdescribed in connection with 602 of FIG. 6 . In some aspects, theSYN-ACK message includes an application server receiver window sizeindicating available buffer space in a receive buffer of the applicationserver. Further, the SYN-ACK modifier component 740 may be configured tomodify the receiver window size in the received SYN-ACK message prior tore-transmitting (e.g., forwarding, transmitting, communicating, etc.)the received SYN-ACK to the tethered device, e.g., as described inconnection with 604 of FIG. 6 .

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowchart of FIG. 6 . Assuch, each block in the aforementioned flowchart of FIG. 6 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

In one configuration, the apparatus 702, and in particular the cellularbaseband processor 704, includes means for receiving a synchronizationacknowledgment (SYN-ACK) message destined for a device tethered to theUE and transmitted by an application server at a network to which the UEis connected. In some aspects, the SYN-ACK message includes anapplication server receiver window size indicating available bufferspace in a receive buffer of the application server. The apparatusincludes means for modifying the receiver window size in the receivedSYN-ACK message prior to re-transmitting (e.g., forwarding,transmitting, communicating, etc.) the received SYN-ACK to the tethereddevice.

The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 702 configured to perform the functionsrecited by the aforementioned means. As described supra, the apparatus702 may include the TX Processor 368, the RX Processor 356, and thecontroller/processor 359. As such, in one configuration, theaforementioned means may be the TX Processor 368, the RX Processor 356,and the controller/processor 359 configured to perform the functionsrecited by the aforementioned means.

RECITATIONS OF SOME ASPECTS OF THE PRESENT DISCLOSURE

Aspect 1: A method of wireless communication performed by a userequipment (UE), the method comprising: receiving a synchronizationacknowledgment (SYN-ACK) message destined for a device tethered to theUE and transmitted by an application server at a network to which the UEis connected, the SYN-ACK message including an application serverreceiver window size indicating available buffer space in a receivebuffer of the application server; and modifying the application serverreceiver window size in the received SYN-ACK message prior totransmitting the received SYN-ACK to the tethered device.

Aspect 2: The method of aspect 1, further comprising determining, priorto the modifying the receiver window size, that an amount of datatransmitted by the tethered device to the application server via the UEexceeds an uplink (UL) buffer threshold of the UE.

Aspect 3: The method of aspect 2, wherein modifying the applicationreceiver window size includes reducing the application receiver windowsize to less than or equal to the UL buffer threshold of the UE.

Aspect 4: The method of any of aspects 1-3, further comprising: prior tothe modifying the receiver window size, monitoring a round trip time(RTT) of a communication cycle between the application server and thetethered device, a communication cycle including data being transmittedby the application server via the UE to the tethered device and anacknowledgement being received at the application server aftertransmission via the UE by the tethered device in response to the databeing received at the tethered device; and determining that the RTT isincreasing over time.

Aspect 5: The method of any of aspects 1-4, further comprising receivinga synchronization (SYN) message destined for the application server viathe UE and transmitted by the tethered device to establish atransmission control protocol (TCP) connection with the network, the SYNincluding a tethered device receiver window size indicating a maximumamount of data the tethered device is configured to receive and buffer.

Aspect 6: The method of any of aspects 1-5, wherein the device tetheredto the UE is a personal computer tethered to the UE via a communicationlink including a universal serial bus (USB) cable, an ethernet cable, aBluetooth® connection or a Wi-Fi® connection.

Aspect 7: A user equipment (UE), comprising: a memory; a processorcoupled to the memory; and a transceiver coupled to the processor, theUE configured to perform the methods of aspects 1-6.

Aspect 8: A user equipment (UE) comprising means for performing themethods of aspects 1-6.

Aspect 9: A non-transitory computer-readable medium (CRM) having programcode recorded thereon, the program code comprises code for causing a UEto perform the methods of aspects 1-6.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of example approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of blocks in the processes/flowcharts may be rearranged.Further, some blocks may be combined or omitted. The accompanying methodclaims present elements of the various blocks in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication performed by a user equipment (UE), the method comprising: receiving a synchronization acknowledgment (SYN-ACK) message destined for a device tethered to the UE and transmitted by an application server at a network to which the UE is connected, the SYN-ACK message including an application server receiver window size indicating available buffer space in a receive buffer of the application server; and modifying the application server receiver window size in the received SYN-ACK message prior to transmitting the received SYN-ACK message to the device tethered to the UE.
 2. The method of claim 1, further comprising determining, prior to the modifying the application server receiver window size, that an amount of data transmitted by the device tethered to the UE to the application server via the UE exceeds an uplink (UL) buffer threshold of the UE.
 3. The method of claim 1, wherein modifying the application server receiver window size includes reducing the application server receiver window size to less than or equal to an uplink (UL) buffer threshold of the UE.
 4. The method of claim 1, further comprising: prior to the modifying the application server receiver window size: monitoring a round trip time (RTT) of a communication cycle between the application server and the device tethered to the UE, wherein the communication cycle includes data being transmitted by the application server via the UE to the device tethered to the UE and an acknowledgement being received at the application server after transmission via the UE by the device tethered to the UE in response to the data being received at the device tethered to the UE; and determining that the RTT is increasing over time.
 5. The method of claim 1, further comprising receiving a synchronization (SYN) message destined for the application server via the UE and transmitted by the device tethered to the UE to establish a transmission control protocol (TCP) connection with the network, the SYN including a tethered device receiver window size indicating a maximum amount of data the device tethered to the UE is configured to receive and buffer.
 6. The method of claim 1, wherein the device tethered to the UE is tethered to the UE via a communication link including a universal serial bus (USB) cable, an ethernet cable, a Bluetooth® connection or a Wi-Fi® connection.
 7. The method of claim 1, further comprising transmitting, to the device tethered to the UE, the received SYN-ACK message including the modified application server receiver window size.
 8. A user equipment (UE), comprising: a memory; a transceiver; and at least one processor coupled to the memory and the transceiver, the transceiver configured to: receive a synchronization acknowledgment (SYN-ACK) message destined for a device tethered to the UE and transmitted by an application server at a network to which the UE is connected, the SYN-ACK message including an application server receiver window size indicating available buffer space in a receive buffer of the application server; and the at least one processor configured to: modify the application server receiver window size in the received SYN-ACK message prior to transmitting the received SYN-ACK message to the device tethered to the UE.
 9. The UE of claim 8, wherein the at least one processor is further configured to determine, prior to modifying the application server receiver window size, that an amount of data transmitted by the device tethered to the UE to the application server via the UE exceeds an uplink (UL) buffer threshold of the UE.
 10. The UE of claim 8, wherein the at least one processor is configured to modify the application server receiver window size by reducing the application server receiver window size to less than or equal to an uplink (UL) buffer threshold of the UE.
 11. The UE of claim 8, wherein the at least one processor is further configured to: prior to modifying the application server receiver window size: monitor a round trip time (RTT) of a communication cycle between the application server and the device tethered to the UE, wherein the communication cycle includes data being transmitted by the application server via the UE to the device tethered to the UE and an acknowledgement being received at the application server after transmission via the UE by the device tethered to the UE in response to the data being received at the device tethered to the UE; and determine that the RTT is increasing over time.
 12. The UE of claim 8, wherein the at least one processor is further configured to receive a synchronization (SYN) message destined for the application server via the UE and transmitted by the device tethered to the UE to establish a transmission control protocol (TCP) connection with the network, the SYN including a device receiver window size indicating a maximum amount of data the device tethered to the UE is configured to receive and buffer.
 13. The UE of claim 8, wherein the device tethered to the UE is tethered to the UE via a communication link including a universal serial bus (USB) cable, an ethernet cable, a Bluetooth® connection or a Wi-Fi® connection.
 14. The UE of claim 8, wherein the at least one processor is further configured to transmit, to the device tethered to the UE, the received SYN-ACK message including the modified application server receiver window size.
 15. A non-transitory computer-readable medium (CRM) having program code recorded thereon for wireless communication by a user equipment (UE), the program code comprising: code for causing the UE to receive a synchronization acknowledgment (SYN-ACK) message destined for a device tethered to the UE and transmitted by an application server at a network to which the UE is connected, the SYN-ACK message including an application server receiver window size indicating available buffer space in a receive buffer of the application server; and code for causing the UE to modify the application server receiver window size in the received SYN-ACK message prior to transmitting the received SYN-ACK message to the device tethered to the UE.
 16. The non-transitory CRM of claim 15, wherein the program code further comprises code for causing the UE to determine, prior to modifying the application server receiver window size, that an amount of data transmitted by the device tethered to the UE to the application server via the UE exceeds an uplink (UL) buffer threshold of the UE.
 17. The non-transitory CRM of claim 15, wherein the code for causing the UE to modify the application server receiver window size causes the UE to reduce the application server receiver window size to less than or equal to an uplink (UL) buffer threshold of the UE.
 18. The non-transitory CRM of claim 15, wherein the program code further comprises code for causing the UE to: prior to the modifying the receiver window size: monitor a round trip time (RTT) of a communication cycle between the application server and the device tethered to the UE prior to the modifying the receiver window size, wherein the communication cycle includes second data being transmitted by the application server via the UE to the device tethered to the UE and an acknowledgement being received at the application server after transmission via the UE by the device tethered to the UE in response to the data being received at the device tethered to the UE; and determine that the RTT is increasing over time.
 19. The non-transitory CRM of claim 15, wherein the program code further comprises code for causing the UE to receive a synchronization (SYN) message destined for the application server via the UE and transmitted by the device tethered to the UE to establish a transmission control protocol (TCP) connection with the network, the SYN including a device receiver window size indicating a maximum amount of data the device tethered to the UE is configured to receive and buffer.
 20. The non-transitory CRM of claim 15, wherein the device tethered to the UE is tethered to the UE via a communication link including a universal serial bus (USB) cable, an ethernet cable, a Bluetooth® connection or a Wi-Fi® connection.
 21. The non-transitory CRM of claim 15, wherein the program code further comprises code for causing the UE to transmit, to the device tethered to the UE, the received SYN-ACK message including the modified application server receiver window size.
 22. A user equipment (UE), comprising: means for receiving a synchronization acknowledgment (SYN-ACK) message destined for a device tethered to the UE and transmitted by an application server at a network to which the UE is connected, the SYN-ACK message including an application server receiver window size indicating available buffer space in a receive buffer of the application server; and means for modifying the application server receiver window size in the received SYN-ACK message prior to transmitting the received SYN-ACK message to the device tethered to the UE.
 23. The UE of claim 22, further comprising means for determining, prior to the modifying the application server receiver window size, that an amount of data transmitted by the device tethered to the UE to the application server via the UE exceeds an uplink (UL) buffer threshold of the UE.
 24. The UE of claim 22, wherein the means for modifying the application server receiver window size includes means for reducing the application server receiver window size to less than or equal to an uplink (UL) buffer threshold of the UE.
 25. The UE of claim 22, further comprising: means for monitoring, prior to the modifying the receiver window size, a round trip time (RTT) of a communication cycle between the application server and the device tethered to the UE, wherein the communication cycle includes data being transmitted by the application server via the UE to the tethered device and an acknowledgement being received at the application server after transmission via the UE by the device tethered to the UE in response to the data being received at the device tethered to the UE; and means for determining that the RTT is increasing over time.
 26. The UE of claim 22, further comprising means for receiving a synchronization (SYN) message destined for the application server via the UE and transmitted by the device tethered to the UE to establish a transmission control protocol (TCP) connection with the network, the SYN including a device receiver window size indicating a maximum amount of data the device tethered to the UE is configured to receive and buffer.
 27. The UE of claim 22, wherein the device tethered to the UE is tethered to the UE via a communication link including a universal serial bus (USB) cable, an ethernet cable, a Bluetooth® connection or a Wi-Fi® connection.
 28. The UE of claim 22, further comprising means for transmitting, to the device tethered to the UE, the received SYN-ACK message including the modified application server receiver window size. 